1. Field of the Invention
The present invention relates to hydraulic jacks and the addition of a spring return mechanism. More specifically, the invention is primarily intended for use on bottle jacks wherein the spring return mechanism automatically returns a handle to an upper position to await the next pumping stroke and wherein a pump rod and pump cylinder assembly of the bottle jack is automatically recharged with fluid.
2. Description of the Prior Art
In the art of hydraulic jacks a bottle jack is a type of jack that is shaped like a bottle and has an external fluid level that encompasses a hydraulic piston or ram centrally located to the bottle itself that is in turn raised by means of a lever or handle that is pushed down upon a small pump connected to the hydraulic piston to discharge fluid to the hydraulic piston or ram. The pump forces the fluid from a fluid reservoir in the small pump into the pump chamber which itself houses a pump rod attached to the handle.
The state of the art is such that the handle is used to depress down the pump rod to discharge the fluid to the hydraulic piston and then handle is pulled back up, i.e. manually, to recharge the pump chamber for the next stroke and depression of the handle. In other words, the stroking of the pump rod is performed manually. U.S. Pat. No. 4,641,815 is an example showing a Hydraulic Jack that requires this manual stroking of the pump rod.
Various devices have also been created in order to overcome the manual nature of stroking the pump rod. U.S. Pat. No. 4,895,042 shows a Pump Lever For A Jack comprising a protrusion near a plunger of a fluid pump and the attachment of a torsion spring 50 which torsion spring is then used to urge the handle to its uppermost position when the handle is freed. This patent shows the use of the torsion spring on a hydraulic service jack such as a standard or high-lift jacks.
In addition, U.S. Pat. No. 5,551,668 shows a Hydraulic Jack With Restorable Lever And Retaining Device disclosing the use of a compression spring 6 on a hydraulic service jack, such as a standard or high-lift jack. The compression spring is placed in a positioning blind hole 25 which is offset a distance from the pump assembly and piston. This location of a compression spring does not form an integral part of the jack and also does not have a collar or yoke to provide alignment to the compression spring to thereby prevent it from bending or buckling during compression. Bending and buckling directs the load away from a plane of movement of the handle and therefore decreases the efficiency of the spring.
Furthermore, U.S. Pat. No. 3,885,449 discloses a Foot Operation For A Pump discloses a helical spring 38 supported by a rod 30 which also is placed so as to offset the piston rod of a pump by a distance. This spring is not placed directly over the piston rod. Finally, U.S. Pat. No. 4,589,669 discloses a Pallet Truck With Hydraulic Lift that utilizes an elongated coil compression spring 101, that while surrounding the pump cylinder 91, does not urge the handle 113 upward and does not utilize a three pinned anchor rod system employed in bottle jacks or hydraulic hand jacks and the like.
What is needed then is a means for automatically returning a handle of a bottle jack, or hydraulic hand jack, to its uppermost position to await a subsequent stroke of the handle and pump rod. Such a device would then allow the user to utilize the bottle jack using a hand or foot without needing to manually pulling the handle upwards after each downward stroke. Furthermore, such a device would act to automatically recharge the pump chamber with fluid, such as hydraulic fluid, after each downward stroke.
Accordingly, it is a principal object of my invention to provide an improved bottle jack that overcomes all of the disadvantages of the lever structures of the prior art.
It is a further object of my invention to provide an improved bottle jack that automatically returns the handle to its uppermost position following the downward depression, or stroke, of the handle and the pump rod to the handle's lowermost position and the manual release of the handle at the lowermost position.
It is a still further object of my invention to provide an improved bottle jack that automatically recharges the pump chamber with the fluid after the handle is manually released following the downward depression, or stroke, of the handle.
It is a further object of my invention to provide an improved bottle jack that is economical, easy to use, and easy to construct, which can be tailored to and retrofitted to an existing bottle jack.
Other objects of my invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or apparent from, the following description and the accompanying drawing figures.